Quantifying Radial Diffusion Rate Through Multi‐MeV Electron Drift Oscillations Driven by Broadband ULF Waves: A Case Study of the September 2019 Geomagnetic Storm.
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| Title: | Quantifying Radial Diffusion Rate Through Multi‐MeV Electron Drift Oscillations Driven by Broadband ULF Waves: A Case Study of the September 2019 Geomagnetic Storm. |
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| Authors: | Zhao, Hong1 (AUTHOR) zzh0054@auburn.edu, Sarris, Theodore E.2,3 (AUTHOR), Li, Xinlin3,4 (AUTHOR), O'Brien, Declan3,4 (AUTHOR), Chen, Rui1 (AUTHOR), Mei, Yang3,4 (AUTHOR), Xiang, Zheng3 (AUTHOR), Baker, Daniel N.3 (AUTHOR) |
| Source: | Journal of Geophysical Research. Space Physics. Feb2026, Vol. 131 Issue 2, p1-17. 17p. |
| Subject Terms: | *Magnetic storms, Electron diffusion, Electrons, Artificial satellites, Radiation belts |
| Abstract: | During the September 2019 geomagnetic storm, long‐lasting, drift‐periodic flux oscillations of multi‐MeV electrons were observed by the REPT instrument on the Van Allen Probes–A. These flux oscillations occurred across the outer belt during the storm main phase, coinciding with enhanced Pc5 ULF wave activity and elevated electron fluxes. During the recovery phase, the oscillations gradually decayed at the center of the outer belt but persisted for days at its inner edge. Using 2D test particle simulations driven by constructed broadband ULF wave fields, we simulated multi‐MeV electron fluxes during two satellite passes and successfully reproduced observed drift‐periodic flux oscillations. The close agreement between simulation and observation confirms a causal relationship between drift‐periodic flux oscillations and resonant interactions of electrons and broadband ULF waves. We further derived the radial diffusion coefficient from the simulation and compared it with empirical models. The magnitude of the resultant radial diffusion coefficient aligns closely with the model by Liu et al. (2016, https://doi.org/10.1002/2015gl067398), though it is lower than those by Brautigam and Albert (2000, https://doi.org/10.1029/1999ja900344) and Ozeke et al. (2014, https://doi.org/10.1002/2013ja019204). The energy‐ and L‐dependence of the diffusion coefficient is also consistent with the model by Liu et al. (2016, https://doi.org/10.1002/2015gl067398). We estimated the uncertainty in the derived radial diffusion coefficient to be approximately half an order of magnitude, primarily limited by the instrument's energy resolution. These results demonstrate the potential of inferring radial diffusion rates from electron flux measurements alone and underscore the importance of high‐energy‐resolution electron measurements for accurately quantifying radiation belt dynamics. Key Points: Long‐lasting, drift‐periodic flux oscillations of multi‐MeV electrons were observed during a moderate storm and reproduced in simulationsThe agreement between simulation and observation confirms that broadband ULF waves cause these flux oscillations via resonant interactionsDerived radial diffusion rates agree with Liu et al. (2016, https://doi.org/10.1002/2015gl067398), with uncertainties associated with the energy resolution of measurements [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
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| Header | DbId: 8gh DbLabel: GreenFILE An: 191834867 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Quantifying Radial Diffusion Rate Through Multi‐MeV Electron Drift Oscillations Driven by Broadband ULF Waves: A Case Study of the September 2019 Geomagnetic Storm. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Zhao%2C+Hong%22">Zhao, Hong</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> zzh0054@auburn.edu</i><br /><searchLink fieldCode="AR" term="%22Sarris%2C+Theodore+E%2E%22">Sarris, Theodore E.</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Li%2C+Xinlin%22">Li, Xinlin</searchLink><relatesTo>3,4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22O'Brien%2C+Declan%22">O'Brien, Declan</searchLink><relatesTo>3,4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Chen%2C+Rui%22">Chen, Rui</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Mei%2C+Yang%22">Mei, Yang</searchLink><relatesTo>3,4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Xiang%2C+Zheng%22">Xiang, Zheng</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Baker%2C+Daniel+N%2E%22">Baker, Daniel N.</searchLink><relatesTo>3</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+Geophysical+Research%2E+Space+Physics%22">Journal of Geophysical Research. Space Physics</searchLink>. Feb2026, Vol. 131 Issue 2, p1-17. 17p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Magnetic+storms%22">Magnetic storms</searchLink><br /><searchLink fieldCode="DE" term="%22Electron+diffusion%22">Electron diffusion</searchLink><br /><searchLink fieldCode="DE" term="%22Electrons%22">Electrons</searchLink><br /><searchLink fieldCode="DE" term="%22Artificial+satellites%22">Artificial satellites</searchLink><br /><searchLink fieldCode="DE" term="%22Radiation+belts%22">Radiation belts</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: During the September 2019 geomagnetic storm, long‐lasting, drift‐periodic flux oscillations of multi‐MeV electrons were observed by the REPT instrument on the Van Allen Probes–A. These flux oscillations occurred across the outer belt during the storm main phase, coinciding with enhanced Pc5 ULF wave activity and elevated electron fluxes. During the recovery phase, the oscillations gradually decayed at the center of the outer belt but persisted for days at its inner edge. Using 2D test particle simulations driven by constructed broadband ULF wave fields, we simulated multi‐MeV electron fluxes during two satellite passes and successfully reproduced observed drift‐periodic flux oscillations. The close agreement between simulation and observation confirms a causal relationship between drift‐periodic flux oscillations and resonant interactions of electrons and broadband ULF waves. We further derived the radial diffusion coefficient from the simulation and compared it with empirical models. The magnitude of the resultant radial diffusion coefficient aligns closely with the model by Liu et al. (2016, https://doi.org/10.1002/2015gl067398), though it is lower than those by Brautigam and Albert (2000, https://doi.org/10.1029/1999ja900344) and Ozeke et al. (2014, https://doi.org/10.1002/2013ja019204). The energy‐ and L‐dependence of the diffusion coefficient is also consistent with the model by Liu et al. (2016, https://doi.org/10.1002/2015gl067398). We estimated the uncertainty in the derived radial diffusion coefficient to be approximately half an order of magnitude, primarily limited by the instrument's energy resolution. These results demonstrate the potential of inferring radial diffusion rates from electron flux measurements alone and underscore the importance of high‐energy‐resolution electron measurements for accurately quantifying radiation belt dynamics. Key Points: Long‐lasting, drift‐periodic flux oscillations of multi‐MeV electrons were observed during a moderate storm and reproduced in simulationsThe agreement between simulation and observation confirms that broadband ULF waves cause these flux oscillations via resonant interactionsDerived radial diffusion rates agree with Liu et al. (2016, https://doi.org/10.1002/2015gl067398), with uncertainties associated with the energy resolution of measurements [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1029/2025JA034549 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 17 StartPage: 1 Subjects: – SubjectFull: Magnetic storms Type: general – SubjectFull: Electron diffusion Type: general – SubjectFull: Electrons Type: general – SubjectFull: Artificial satellites Type: general – SubjectFull: Radiation belts Type: general Titles: – TitleFull: Quantifying Radial Diffusion Rate Through Multi‐MeV Electron Drift Oscillations Driven by Broadband ULF Waves: A Case Study of the September 2019 Geomagnetic Storm. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Zhao, Hong – PersonEntity: Name: NameFull: Sarris, Theodore E. – PersonEntity: Name: NameFull: Li, Xinlin – PersonEntity: Name: NameFull: O'Brien, Declan – PersonEntity: Name: NameFull: Chen, Rui – PersonEntity: Name: NameFull: Mei, Yang – PersonEntity: Name: NameFull: Xiang, Zheng – PersonEntity: Name: NameFull: Baker, Daniel N. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 02 Text: Feb2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 21699380 Numbering: – Type: volume Value: 131 – Type: issue Value: 2 Titles: – TitleFull: Journal of Geophysical Research. Space Physics Type: main |
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